Search Publications
Cloning Hubble Deep Fields. I. A Model-independent Measurement of Galaxy Evolution
Broadhurst, Tom; Bouwens, Rychard; Silk, Joseph
We present a model-independent method of quantifying galaxy evolution in high-resolution images, a method which we apply to the Hubble Deep Field (HDF). Our procedure is to k-correct all pixels belonging to the images of a complete set of bright galaxies and then to replicate each galaxy image to higher redshift by the product of its space density…
On the use of the HIPPARCOS intermediate astrometric data
Evans, D. W.; van Leeuwen, F.
With the publication of the Hipparcos catalogue, astrometric data of unprecedented quality and quantity has become available, providing parallaxes, positions and proper motions free from systematic errors down to a level of at least 0.1 mas and 0.1 mas y(-1) . The Hipparcos catalogue, however, contains not only these ``ready-to-use'' positions, pa…
Discovery of CO_2 emission in AGB stars with the 13mu M dust feature
Waters, L. B. F. M.; Feuchtgruber, H.; Justtanont, K. +4 more
We have detected strong emission lines at 13.48, 13.87, 14.97, 15.40 and 16.28mu m in the ISO/SWS spectra of O-rich AGB stars. These lines are only found in the spectra of Miras and semi-regular variables when they also show the 13mu m dust emission feature. The lines appear just resolved in the high-resolution (AOT06, resolution ~ 1500) SWS spect…
The Morphology and Kinematics of the Complex Polypolar Planetary Nebula NGC 2440
López, J. A.; Meaburn, J.; Holloway, A. J. +1 more
Spatially resolved profiles of the Hα, [N II] 6584 Å, and [O III] 5007 Å lines have been obtained with the Manchester echelle spectrometer combined with the 2.1 m San Pedro Mártir telescope over the planetary nebula NGC 2440. The resulting position-velocity (PV) arrays are compared with ground-based and HST archival imagery, revealing the complex …
Discovery of Red Selected Arcs at Z = 4.04 behind Abell 2390
Broadhurst, Tom; Frye, Brenda
We describe the properties of three red arcs discovered at z=4.04 behind the cluster A2390 (z=0.23). We demonstrate that these arcs are images of a single galaxy where lensing is compounded by an elliptical cluster member near the critical curve of the cluster. The combined magnification is estimated to be ~20 using Hubble Space Telescope images, …
Coronal line-width variations
Doyle, J. G.; Banerjee, D.; Perez, M. E.
Line-width measurements of the coronal ion Siviii confirm earlier observations which show an increase in the non-thermal velocity above the solar limb. The present data, taken at the equatorial limb, show an increase from 24 km s-1 at the limb to 28 km s-1 some 25000 km above the limb. The electron density as measured from th…
Differences in the O7+/O6+ ratio of magnetic cloud and non-cloud coronal mass ejections
Livi, S.; Woch, J.; Schwenn, R. +7 more
On its trajectory to Jupiter and over the poles of the Sun the Ulysses spacecraft has observed a considerable number of Coronal Mass Ejection (CME) transients in slow and in fast solar wind streams. The analysis of the magnetic field topology and the O7+/O6+ charge state ratio of 56 of these events has yielded strong evidence…
Dust, Gas, and the Evolutionary Status of the Radio Galaxy 8C 1435+635 at z = 4.25
Ivison, R. J.; Dunlop, J. S.; Stevens, J. A. +8 more
We present the results of new rest-frame far-IR observations of the z = 4.25 radio galaxy 8C 1435+635, which not only confirm that it contains an enormous quantity of dust (as first inferred from its millimeter-wave detection by Ivison in 1995), but also allow the first meaningful constraints to be placed on the mass of this dust and associated ga…
High-Resolution Observations of the Solar Hydrogen Lyman Lines in the Quiet Sun with the SUMER Instrument on SOHO
Wilhelm, K.; Mariska, J. T.; Warren, H. P.
We present high-resolution observations of the higher H Lyman series lines taken with the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) experiment flown on the Solar and Heliospheric Observatory (SOHO) spacecraft. We have used systematic observations extending from disk center to the solar limb to compute average profiles for represe…
Galaxy surface brightness and size evolution to z~4
Im, M.; Griffiths, R. E.; Roche, N. +2 more
Using HST WFPC2 data, we estimate half-light radii, morphological classifications and rest-frame, blue-band absolute magnitudes for 270 galaxies with spectroscopic redshifts from z~0 to z=3.43, and 77 thought from their colours to be at 2.0<=z<=4.5. The mean blue-band surface brightness decreases by ~2 mag along the Hubble sequence from elli…